996 Clutch Air Line

Hi all, Got a 996 C2 replaced clutch slave and clutch master cylinder, and bled clutch with Motive power bleeder, worked fine for a few weeks, but now during hard accel on freeway, go through 1-4 fine but 5-6 are hard to shift to. Then after freeway driving at high speed back to stop and go traffic. Clutch has air and difficult to go shift 1-6. As a note I have bled the system 4 times already using the same procedure using Motive power bleeder. No leaks that can be seen on floor and no decrease volume of DOT4. Here is my theory, it has been observed that long drives 100-120 miles WITHOUT to much clutch usage (freeway driving) the clutch goes soft and has the symptoms of air in line, and a clutch bleed is necessary to get it back to normal clutch pressure. I pulled the schematic of the clutch hydraulic system, and I see one point of concern It also coincides to my theory, that heat or long drives can induce the air/gas in the clutch line. The component in question is 14, hose with rubber that connects to slave. This hose line could be degraded and softens and swells. As a note, this hose also is nearly in contact with the coolant return pipe to the radiator. Could this be the culprit? Any feedback is appreciated.

When you bled your clutch, did you hold the pedal to the floor while bleeding?

Yes clutch pedal all the way down when bleeding with Motive Bleeder.

We see and bleed these systems all the time in the shop using the Motive unit, and if you are getting air into the system (as evidenced by air bubbles upon subsequent re bleeds), you have a bad seal, probably in the slave unit itself. The hose could be bad, but that would be a rarity. These systems are not known for leaking otherwise,

Thanks for the reply its the 2nd Slave I replaced thinking its the slave. I also replaced the master too. Can't think of anything else other than then hose.

If the hose is leaking, it should be wet. In all the years I've worked on these cars, I have only replaced one hose, and that was because the owner accidentally damaged it.

Hose is not leaking/and no leaks can be found anywhere in the system. This is my second slave thinking first replacement slave was defective. Same symptoms as first slave, and actually seems to be getting worse-less miles driven before clutch pedal gets soft. Just cant think its another defective slave since during my long drive on freeway 100+ miles, pedal starts to soften, since I may have only used clutch about 12 times. Last observation, was my wife actuated clutch pedal while I am seeing and feeling hose. Hose moved a little and also a very slight bulging of the hose. Keep in mind this is in the cold state, don't know what happens in normal operating temps.

Are you using factory or after market slave cylinders? We have had absolutely no luck with aftermarket units.

FTE was the brand that I purchased from Pelican. The probability of both of them not functioning correctly seems very low, and the latest one has only 50 miles on it before I observed the symptoms.

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Don't bet on it, we never had any luck with FTE, which is an aftermarket supplier. We have seen units from them that did not work right out of the box. Unfortunately, with a lot of Porsche aftermarket parts, you get exactly what you paid for them when you cheap out.

10 years later, I'm having the same issue. Ferdzz, did you ever figure this out?